M.M. Khalil1, K. Bai2, F. Ye2, C. Mwakio3, H. Musau3, B. Akinyi3, J. Macleod2,4, R.M. Kauffmann2,3,5 4Kenyatta University, Nairobi, Kenya 5Vanderbilt Institute for Global Health, Nashville, TN, USA 1Vanderbilt University School of Medicine, Nashville, TN, USA 2Vanderbilt University Medical Center, Nashville, TN, USA 3AIC Kijabe Hospital, Kijabe, Kenya
Introduction:
Breast cancer remains one of the leading causes of morbidity and mortality worldwide. This is especially true for regions of sub-Saharan Africa where little is known about how age of diagnosis relates to breast cancer outcomes. Our study evaluated differences in patient and tumor characteristics and outcomes between those diagnosed with early-age onset and those diagnosed with average-age onset breast cancer at a tertiary referral hospital in rural central Kenya.
Methods:
We performed a retrospective study evaluating a population of 963 patients diagnosed with breast cancer at Kijabe Hospital, dividing cohorts into young onset (45 years at diagnosis). We analyzed patient and tumor characteristics including TNM staging, hormone receptor status, survival, and recurrence, as well as social factors such as distance traveled to the hospital. Univariate analysis was performed, and Cox regression models were fit to analyze overall and disease-free survival. The primary outcome was overall survival, and the secondary outcome was disease-free survival.
Results:
There was no difference in the groups when evaluating tumor type (p =0.06), tumor grade (p=0.06), hormone receptor positivity (p =0.29) or presence of metastatic disease at diagnosis (p=0.27). Patients with early-onset disease were more likely to present with larger tumor size T3 or T4 (38% vs. 22%, p<0.01) and more likely to present with larger nodal burden (N2 25% vs. 13%, and N3 8% vs. 5%, p<0.01). There was no significant difference in overall or disease-free survival between the two groups (p=0.35 and p=0.5, respectively). Presence of N3 disease and metastases were significantly correlated with overall mortality (p=0.003 and p=0.015 respectively). Disease-free survival was not affected by age, tumor size or nodal disease burden.
Conclusion:
Our results show that, patients with young onset breast cancer presented with larger tumors and more nodal disease. This suggests delays in presentation, which may be due to gaps in screening, lack of education about breast cancer signs, or familial and cultural barriers that delay presentation. Despite this, overall and disease-free survival were not different between the groups, suggesting that once diagnosed, younger patients may be treated more aggressively or have a better response to treatment than older patients. Additional studies are needed to explore the reasons that the survival of patients with young-onset breast cancer in Kenya is not affected by size of the primary tumor or nodal burden of disease at diagnosis.